1. Field of the Invention
The present invention relates to an inner-rotor motor.
2. Description of the Related Art
In recent years, there has been a demand for high rotational accuracy of inner-rotor motors.
In addition, in recent years, with an increase in the number of electronic devices used in homes and workplaces, there has been a demand for reducing noise caused by various electronic devices, such as, for example, household electrical appliances and cooking appliances. Various techniques have been devised to reduce noise of motors, such as, for example, using inner-rotor motors and increasing rotational accuracy of the motors as greatly as possible.
In a known motor, a circuit board on which a Hall IC is provided is arranged inside a motor case, and the rotational position of a rotor defined by a permanent magnet is detected to realize high rotational accuracy. Such a known motor is described, for example, in JP-A 2005-102370.
However, in the case where there is a demand for a still higher degree of rotational accuracy, only detecting the rotational position of the rotor may be insufficient. In this case, a method of correcting dynamic balance of a rotor portion of the motor may be adopted, for example. However, in the case of the known motor disclosed in JP-A 2005-102370, a self-cooling fan arranged to cool electronic components and windings is arranged on one side of the rotor, and this makes it difficult to correct the dynamic balance.